Wow thanks for the quick turnaround! The fix is a bit awkward compared to auto detecting, but it works!
I actually did a few tests and found a full solution for Samsung tablets! Samsung's browser has proper palm rejection, unlike Chrome, so running Manabit in it works flawlessly. Full palm rejection and ability to pan and zoom using fingers without the need to toggle modes. I couldn't get rotation to work though, not sure the rotation gesture is supposed to rotate individual elements or the canvas though? So maybe I'm just trying to do it in the wrong context?
Installing and running it as an app on my tablet also works... most of time. There seems to be a Samsung bug where it doesn't have palm rejection when the app is launched in portrait mode, but does when it's launched landscape. Can change modes after no problem though. It's weird, but not a big deal. Just mentioning in case someone else is looking for a solution to this problem in the future.
Two gestures from other drawing apps that'd be very nice to have are undo (tap with two fingers) and redo (tap with three fingers).
In any case it's great to finally have a pixel art app that runs on android with good clean UX!